Magnetic resonance imaging has been developed as an imaging technique adapted to obtain both images of anatomical features of human patients as well as some aspects of the functional activities and characteristics of biological tissue. These images have medical diagnostic value in determining the state of the health of the tissue examined. Unlike the situation with fluoroscopic imaging, a patient undergoing magnetic resonance imaging procedure may remain in the active imaging system for a significant amount of time, e.g. a half-hour or more, without suffering any adverse effects.
In a magnetic-resonance imaging process, a patient is typically aligned to place the portion of the patient's anatomy to be examined in the imaging volume of the magnetic-resonance imaging apparatus. Such an magnetic-resonance imaging apparatus typically comprises a primary electromagnet for supplying a constant magnetic field (B0) which, by convention, is along the z-axis and is substantially homogeneous over the imaging volume and secondary electromagnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x1, x2 and x3, respectively). The magnetic-resonance imaging apparatus also comprises one or more RF (radio frequency) coils that provide excitation and detection of the magnetic-resonance imaging induced signals in the patient's body.
The gradient fields are switched ON and OFF at different rates depending on the magnetic-resonance imaging scan sequence used. In some cases, this may result in a changing magnetic field on the order of dB/dt=50 T/s. The frequency that a gradient field may be turned ON can be between 200 Hz to about 300 kHz.
For a single loop with a fixed area, Lenz's law can be stated as:EMF=−A@dB/dt where A is the area vector, B is the magnetic field vector, and “@” is the vector scalar product. This equation indicates that an electro-motive-force (EMF) is developed in any loop that encircles a changing magnetic field.
In a magnetic-resonance imaging system, there is applied to the biological sample (patient) a switched gradient field in all 3 coordinate directions (x-, y-, z-directions). If the patient has an implanted heart pacemaker (or other implanted devices having conductive components) the switched gradient magnetic fields (an alternating magnetic field) may cause:                1. Erroneous signals to be induced/generated in a sensing lead or device or circuit;        2. Damage to electronics; and/or        3. Harmful stimulation of tissue, e.g. heart muscle, nerves, etc.        
As noted above, the use of the magnetic-resonance imaging process with patients who have implanted medical assist devices; such as cardiac assist devices or implanted insulin pumps; often presents problems. As is known to those skilled in the art, implantable devices (such as implantable pulse generators (IPGs) and cardioverter/defibrillator/pacemakers (CDPs)) are sensitive to a variety of forms of electromagnetic interference (EMI) because these enumerated devices include sensing and logic systems that respond to low-level electrical signals emanating from the monitored tissue region of the patient. Since the sensing systems and conductive elements of these implantable devices are responsive to changes in local electromagnetic fields, the implanted devices are vulnerable to external sources of severe electromagnetic noise, and in particular, to electromagnetic fields emitted during the magnetic resonance imaging (magnetic-resonance imaging) procedure. Thus, patients with implantable devices are generally advised not to undergo magnetic resonance imaging (magnetic-resonance imaging) procedures.
To more appreciate the problem, the use of implantable cardiac assist devices during a magnetic-resonance imaging process will be briefly discussed.
The human heart may suffer from two classes of rhythmic disorders or arrhythmias: bradycardia and tachyarrhythmia. Bradycardia occurs when the heart beats too slowly, and may be treated by a common implantable pacemaker delivering low voltage (about 3 Volts) pacing pulses.
The common implantable pacemaker is usually contained within a hermetically sealed enclosure, in order to protect the operational components of the device from the harsh environment of the body, as well as to protect the body from the device.
The common implantable pacemaker operates in conjunction with one or more electrically conductive leads, adapted to conduct electrical stimulating pulses to sites within the patient's heart, and to communicate sensed signals from those sites back to the implanted device.
Furthermore, the common implantable pacemaker typically has a metal case and a connector block mounted to the metal case that includes receptacles for leads which may be used for electrical stimulation or which may be used for sensing of physiological signals. The battery and the circuitry associated with the common implantable pacemaker are hermetically sealed within the case. Electrical interfaces are employed to connect the leads outside the metal case with the medical device circuitry and the battery inside the metal case.
Electrical interfaces serve the purpose of providing an electrical circuit path extending from the interior of a hermetically sealed metal case to an external point outside the case while maintaining the hermetic seal of the case. A conductive path is provided through the interface by a conductive pin that is electrically insulated from the case itself.
Such interfaces typically include a ferrule that permits attachment of the interface to the case, the conductive pin, and a hermetic glass or ceramic seal that supports the pin within the ferrule and isolates the pin from the metal case.
A common implantable pacemaker can, under some circumstances, be susceptible to electrical interference such that the desired functionality of the pacemaker is impaired. For example, common implantable pacemaker requires protection against electrical interference from electromagnetic interference (EMI), defibrillation pulses, electrostatic discharge, or other generally large voltages or currents generated by other devices external to the medical device. As noted above, more recently, it has become crucial that cardiac assist systems be protected from magnetic-resonance imaging sources.
Such electrical interference can damage the circuitry of the cardiac assist systems or cause interference in the proper operation or functionality of the cardiac assist systems. For example, damage may occur due to high voltages or excessive currents introduced into the cardiac assist system.
Moreover, problems are realized when the placement of the implant is next to particular organs. For example, when a pacemaker is placed in the upper chest and the lead tip is placed into the heart, a loop (an electrical loop) is created. A changing magnetic field (the switched gradient field) over the area of the loop (through the area of the loop) will cause an induced voltage (and current) across the heart. This induced voltage (current) can stimulate the heart inappropriately and can cause heart damage or death.
Therefore, it is desirable to provide a medical device or system that reduces or eliminates the undesirable effects of changing magnetic fields from a magnetic-resonance imaging system on the medical devices and/or patients undergoing medical procedures or that have temporary or permanent implanted materials and/or devices with conducting components.
A voltage compensation unit reduces the effects of induced voltages upon a device to a safe level. The voltage compensation unit includes a sensing circuit to sense voltages induced in conductive components of the device, the voltages being induced by changing magnetic fields and a compensation circuit, operatively connected to the sensing circuit and responsive thereto, to provide opposing voltages to the device to reduce the effects of induced voltages caused by changing magnetic fields.
A voltage compensation unit reduces the effects of induced voltages upon a tissue invasive medical tool to a safe level. The voltage compensation unit includes a sensing circuit to sense voltages induced in conductive components of the medical tool, the voltages being induced by changing magnetic fields; a compensation circuit, operatively connected to the sensing circuit and responsive thereto, to provide opposing voltages to the medical tool to reduce the effects of induced voltages caused by changing magnetic fields; and a connection device to provide an electrical connection between the sensing circuit and the compensation circuit and the medical tool.
A voltage compensation unit reduces the effects of induced voltages upon a device to a safe level. The voltage compensation unit includes a communication circuit, communicatively linked to a magnetic-resonance imaging system, to receive information associated with a start and end of an application of changing magnetic fields produced by the magnetic-resonance imaging system and a compensation circuit, operatively connected to the communication circuit and responsive thereto, to synchronize application of opposing voltages to the device with the sensed changing magnetic fields, the opposing voltages reducing the effects of induced voltages caused by the changing magnetic fields.
A voltage compensation unit reduces the effects of induced voltages upon a device to a safe level. The voltage compensation unit includes a communication circuit, communicatively linked to a magnetic-resonance imaging system, to receive information associated with a start and end of an application of changing magnetic fields produced by the magnetic-resonance imaging system and a compensation circuit, operatively connected to the communication circuit and responsive thereto, to apply opposing voltages to the device, the opposing voltages reducing the effects of induced voltages caused by the changing magnetic fields.
A voltage compensation unit reduces the effects of induced voltages upon a device having a single wire line, the single wire line having a balanced characteristic impedance. The voltage compensation unit includes a tunable compensation circuit, operatively connected to the wire line, to apply supplemental impedance to the wire line, the supplemental impedance causing the characteristic impedance of the wire line to become unbalanced, thereby reducing the effects of induced voltages caused by changing magnetic fields.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region and a coil that generates a voltage due to a changing magnetic-resonance imaging electromagnetic field opposite to that which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region and a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region and three orthogonally planar coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region; a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and plurality of coils, to operatively connect a number of the plurality of coils in response to the measured strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region; three orthogonally planar coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and the coils, to operatively connect a number of the coils in response to the measured strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region; a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and plurality of coils, to operatively connect a number of the plurality of coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region; three orthogonally planar coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and the coils, to operatively connect a number of the coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region and a coil that generates a voltage induced by a changing magnetic-resonance imaging electromagnetic field opposite to a voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region and a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region and three orthogonally planar coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region; a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and plurality of coils, to operatively connect a number of the plurality of coils in response to the measured strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region; three orthogonally planar coil, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and plurality of coils, to operatively connect a number of the plurality of coils in response to the measured strength of voltages induced by changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region; a plurality of coils, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and the coils, to operatively connect a number of the coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region; three orthogonally planar coil, each coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and the coils, to operatively connect a number of the coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead component for a medical device reduces the effects of magnetic-resonance imaging induced signals. The electrical lead component includes a medical device electrical lead capable of providing an electrical path to a desired tissue region; a voltage source; a sensor to sense voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and voltage source, to operatively connect the voltage source to the medical device electrical lead in response to the sensed voltage induced by the changing magnetic-resonance imaging electromagnetic field such that the voltage source provides a voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A device for a medical device reduces the effects of magnetic-resonance imaging induced signals. The medical device includes a medical device capable of providing medical treatment to a desired tissue region; a voltage source; a sensor to sense voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and voltage source, to operatively connect the voltage source to the medical device in response to the sensed voltage induced by the changing magnetic-resonance imaging electromagnetic field such that the voltage source provides a voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands and an insulating coating formed over a portion of the two coiled conductive strands such that an inline inductive element is formed, the current flowing along a curvature of the two coiled conductive strands in the insulating coated portion of the two coiled conductive strands.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands and an adjustable resistive material formed over a portion of the two coiled conductive strands such that an inline inductive element is formed, the current flowing along a curvature of the two coiled conductive strands in the adjustable resistive material portion of the two coiled conductive strands.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand and an insulating coating formed over a portion of the coiled conductive strand such that an inline inductive element is formed, the current flowing along a curvature of the coiled conductive strand in the insulating coated portion of the coiled conductive strand.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand and an adjustable resistive material formed over a portion of the coiled conductive strand such that an inline inductive element is formed, the current flowing along a curvature of the coiled conductive strand in the adjustable resistive material portion of the coiled conductive strand.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands; a first insulating coating formed over a first portion of the two coiled conductive strands such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of the two coiled conductive strands in the first insulating coated portion of two coiled conductive strands; and a second insulating coating formed over a second portion of the two coiled conductive strands such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of the two coiled conductive strands in the second insulating coated portion of two coiled conductive strands. The first inductance is different from the second inductance.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes two coiled conductive strands forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strands; a first adjustable resistive material formed over a first portion of the two coiled conductive strands such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of the two coiled conductive strands in the first adjustable resistive material portion of the two coiled conductive strands; and a second adjustable resistive material formed over a second portion of the two coiled conductive strands such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of the two coiled conductive strands in the second adjustable resistive material portion of the two coiled conductive strands. The first inductance is different from the second inductance.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand; a first insulating coating formed over a first portion of the coiled conductive strand such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of the coiled conductive strand in the first insulating coated portion of the coiled conductive strand; and a second insulating coating formed over a second portion of the coiled conductive strand such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of the coiled conductive strand in the second insulating coated portion of the coiled conductive strand. The first inductance is different from the second inductance.
A lead for medical applications reduces the effects of magnetic-resonance imaging induced signals. The lead includes a coiled conductive strand forming a spring-like configuration such that current flows over a surface thereof, through contact points between adjacent loops of the coiled conductive strand; a first adjustable resistive material formed over a first portion of the coiled conductive strand such that a first inline inductive element having a first inductance is formed, the current flowing along a curvature of the coiled conductive strand in the first adjustable resistive material portion of the coiled conductive strand; and a second adjustable resistive material formed over a second portion of the coiled conductive strand such that a second inline inductive element having a second inductance is formed, the current flowing along a curvature of the coiled conductive strand in the second adjustable resistive material portion of the coiled conductive strand. The first inductance is different from the second inductance.
An electrical lead is capable of providing an electrical path to a desired tissue region, including a coil that generates a voltage due to a changing magnetic-resonance imaging electromagnetic field opposite to that which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the coil so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including a plurality of coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the plurality of coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including planar coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the planar coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including a plurality of coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and plurality of coils, to operatively connect a number of the plurality of coils in response to the measured strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including planar coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a sensor to measure a strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field; and a switching device, operatively connected to the sensor and the coils, to operatively connect a number of the coils in response to the measured strength of voltages induced by the changing magnetic-resonance imaging electromagnetic field such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the planar coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including a plurality of coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and plurality of coils, to operatively connect a number of the plurality of coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the electrical lead without the coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead is capable of providing an electrical path to a desired tissue region, including planar coils, at least one coil generating a voltage due to a changing magnetic-resonance imaging electromagnetic field; a transceiver to receive a signal indicating a number of coils to be connected; and a switching device, operatively connected to the transceiver and the coils, to operatively connect a number of the coils in response to the received signal indicating the number of coils to be connected such that a combination of voltages due to a changing magnetic-resonance imaging electromagnetic field provides a combined voltage that is opposite to the voltage which would be induced by the changing magnetic-resonance imaging electromagnetic field in the medical device electrical lead without the planar coils so as to reduce voltages induced by the changing magnetic-resonance imaging electromagnetic field.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a RF choke, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The RF choke allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a RF filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The RF filter allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a notch filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The notch filter allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a bandpass filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The bandpass filter allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and an inductor, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The inductor allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a RF choke, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The RF choke allows a therapeutic signal to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a RF filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The RF filter allows a therapeutic signal to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a notch filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The notch filter allows a therapeutic signal to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a bandpass filter, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The bandpass filter allows a therapeutic signal to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and an inductor, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The inductor allows a therapeutic signal to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a tank circuit, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The tank circuit allows a signal corresponding to a measured characteristic of the tissue region to pass therethrough.
An electrical lead includes an electrical strand to provide an electrical path between a tissue region and a medical device and a tank circuit, operatively connected to the electrical strand, to significantly reduce currents induced by a changing MRI electromagnetic field in the electrical strand. The tank circuit allows a therapeutic signal to pass therethrough.